We will determine the regional cerebral glucose metabolism and regional cerebral blood flow in non sleep deprived awake cats and in sleep deprived awake cats, as well as in sleep deprived cats during paradoxical (REM) sleep and in slow wave sleep. Comparison of the sleep deprived controls and REM sleep animals will allow us to determine in which areas of the brain REM sleep causes significant changes in glucose metabolism. This pattern of altered glucose metabolism will be compared to the pattern of altered cerebral blood flow seen in REM sleep to determine if all blood flow changes can be explained by changes in cerebral glucose metabolism. Similar comparisons will be made between the sleep deprived control animals and the animals in slow wave sleep. Comparing the non sleep deprived animals with the sleep deprived animals will allow us to determine the effect of sleep deprivation on both regional cerebral glucose consumption and regional cerebral blood flow.